Heretofore, an optical semiconductor light-emitting device with a light-emitting element mounted therein is so planned that an optical semiconductor element 2 is mounted on a metal lead frame 1, and an insulating resin layer 3 is formed to surround the optical semiconductor element 2 except the upper side thereof, as shown in FIG. 1. In FIG. 1, 4 is a bonding wire that electrically connects the electrode circuit (not shown) formed on the metal lead frame 1 to the optical semiconductor element 2.
In such an optical semiconductor light-emitting device, the insulating resin layer 3 is formed of a thermoplastic resin such as typically polyphthalamide resin (PPA) or the like through injection molding. A white pigment is generally incorporated into the thermoplastic resin to reflect the light emitted by the optical semiconductor element 2 and impart directivity thereto (see Patent Document 1).
In case where high heat resistance is required, a ceramic material containing sintered alumina is mainly used to form a part in place of the insulating resin layer 3 (see Patent Document 2). However, the formation of the part corresponding to the insulating resin layer 3 from the ceramic material is problematic in view of the suitability for mass production and cost of such packages, etc, and further, the shape reproducibility of the reflector (reflective part).
Given the situation, recently, for solving the problems, the mainstream in producing optical semiconductor light-emitting devices is going to be transfer molding with a thermosetting resin. The thermosetting resin forming material for use in production through transfer molding is generally an epoxy resin composition including a combination of an epoxy resin such as a bisphenol A epoxy resin or the like and a curing agent such as an acid anhydride or the like, since the surface of the cured material thereof is required to have high-level light reflectivity.
In that situation, recently, the brightness of light-emitting devices is being elevated further, and a material having higher heat resistance and light resistance than before is desired for the resin composition for use for optical semiconductor light-emitting devices. For example, as a method for enhancing the heat resistance and the light resistance of the resin composition for use for optical semiconductor light-emitting devices, an alicyclic epoxy resin is used for light absorption to suppress light degradation, and this is employed in some quarters (see Patent Document 3).    Patent Document 1: JP-A-2002-283498    Patent Document 2: JP-A-2004-288937    Patent Document JP-A-2004-339319